Il Treno di John Cage

A mesostic poem is a form of inclusion poetry, or acrostic poem in which the "hidden" or included word, phrase, or name is seen vertically in a central spine instead of at the beginning or end (or both for a "double acrostic") of each line. The form was popularized (if such a thing is possible with such esoteric poetry) by John Cage, who used the term to describe a particular form of inclusion poetry that had compositional rules beyond simply holding the inclusion word or phrase down a central spine.